Heretofore, several methods of producing a color filter used for a display for a liquid crystal TV, a personal computer and the like, have been known. Such known methods include:
(1) a dyeing method which comprises dyeing a gelatin layer formed on a substrate, forming a photo-resist layer and curing the resist with a ultraviolet ray;
(2) a dispersion method which comprises dispersing a dye in a resist material, and then curing the resist material with the ultraviolet ray;
(3) a printing method which comprises directly printing a pattern for a coloring matter film and the like on a substrate; and
(4) an electrolytic method which comprises forming a dispersion of a dye in a suitable solvent, and subjecting the dispersion to electrodepositing treatment utilizing an electrode formed on the substrate.
However, the above dyeing method (1) has a disadvantage in that the resultant filter has poor light resistance. The above dispersion method (2) shows a poor productivity due to a complexity of the steps. Further, the above printing method (3) is unsuperior in accuracy and light resistance. On the contrary, the above electrodeposition method (4) is advantageous since the resultant filter has good light resistance and high heat resistance. However, according to the method (4), the resultant filter needs a transparent electrode for forming a coloring matter layer, and needs, on its surface, an electrode for driving a liquid crystal as is the same case with the above methods (1) to (3).
On the other hand, as a process for producing a color filter which is capable of forming a conductive coloring matter layer, Japanese Patent Application Laid-Open Gazette No. 63-243298 discloses a micellar disruption method which comprises forming a transparent electrode in a desired shape on an insulating substrate, and forming a porous hydrophobic coloring matter film on the electrode by a micellar disruption method.
Recently, a light-shielding film is indispensable to make a display device such as a color filter, a liquid crystal display material, an electron display material, and a color display. These display devices have widely been used in several fields such as a lap-top personal computer, a note type personal computer, an audio equipment, an inside panel for an automotive, a clock, a calculator, a video cassette deck, a facsimile, a communication equipment, a game machine and a measurement equipment.
For example, in the fields of a color filter, a light-shielding film is used as a black matrix to be formed between each of picture elements such as red (R), green (G) and blue (B). Such black matrix is used to avoid lowering contrast and color purity due to leaked light.
Heretofore, in the case of forming each picture element (coloring matter layer) such as a color filter by a printing method, a dispersion method or a dyeing method, there have been used a carbon type photo-resist material and a chromium film in many cases.
However, the use of the carbon type photo-resist material or the chromium film cannot give an electrode for driving a liquid crystal and an electrode for forming a coloring matter film at the same time due to their conductivity. More specifically, when a black matrix is first formed, using the photo-resist material or the chromium film, on an ITO electrode on which a pattern was formed for forming a coloring matter layer, the ITO electrode will be electrically connected with a right and left side electrodes. Thus, a coloring matter layer cannot be formed by a micellar disruption method and the like. On the contrary, when a black matrix is formed after a coloring matter layer is formed, there will be a problem that a liquid crystal cannot work due to electrical connection between the ITO electrode and a right and left side electrodes during liquid crystal operation. Accordingly, the use of the carbon type photo-resist material results in a problem that a micellar disruption method and an electro-deposition method cannot be used to form a coloring matter layer.
Accordingly, it has been desired to develop a resist for a light-shielding film which has an insulating property. Thus, organic dye type photo-resist materials have been developed. The light-shielding film made from the conventional insulating organic dye type photo-resist material is formed by a photo-lithography method by mixing three kinds of photo-resists including dyes for red (R), green (G) and blue (B), or two kinds of photo-resists including dyes of red (R) and blue (B). Thus, the resultant light-shielding film has poor light-shielding ratio. To obtain a sufficient light-shielding ratio, it is necessary to make film thicker.
The present invention was made in view of the above situations, and has its object to provide a process for producing a color filter in which a transparent electrode can be used both for forming a coloring matter layer during the color filter preparation and for driving a liquid crystal after the color filter has been produced. Further, rt is another object of the present invention to provide a resist for a light-shielding film capable of forming a light-shielding film having an good insulating property and a high light-shielding ratio.